Power-driven hand truck



May 9, 1950 F. sToNER PowER-DRrvEN HAND TRUCK Original Filed July l2, 1945 5 Sheets-Sheet 1 llllll www @w we# m mmm SToA/m e, @am

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F. sToNER 2,507,357

POWER-DRIVEN HAND TRUCK 5 Sheets-Sheet 3 May 9, 1950 Original Filed July l2, 1945 May 9, 1950 F. sToNER POWER-DRIVEN HAND TRUCK Original Filed July 12, 1945 5 Sheets-Sheet 4 FI G'. 5

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May 9, 1950 F. s'roNER POWER-DRIVEN HAND TRUCK 5 Sheets-Sheet 5 Original Filed July 12,1945

FIG. 6

31' 370 5I: :slib

III

FIG. '7

NVENTOR. JAA-,WIL XM rial handling mechanism 3. I may provide two pairs of wheels IU which are mounted on swingable yokes or devices (later referred to) adapted to raise and lower the outer end portion of the load handling mechanism 3. In the form of construction shown the materialhandling mechanism 3 is movably connected to the frame I, and the wheel 9 and wheels IG co-operate to support the frame I, when the truck is at rest or is being driven, irrespective of whether the mechanism 3 is raised or lowered and loaded or unloaded.

As shown, the driving meansfor the wheel 9' is of the hydraulic rotary type and is incorporated therein and the power supply for the driving means and its valve mechanism are unitarily connected with the mounting for the traction and steerable mechanism to simplify the assembly and insure a direct connection between the power supply and the driving means.

The combined traction and steerable mechanism comprises the following: II indicates an axle xedly supported at its opposite ends in arms IIa which are fixed to and depend from a disk I2. The marginal portion of the disk I2 engages a ring bearing I3 of the anti-friction type, provided between the disk and marginal portion of the opening Ic, whereby the mechanism is bodily rotatable about the axis of the bearing I3 for steering the truck when the latter is being power driven or manually moved. The axle ll is formed with ducts I4, I4', extending inwardly from its opposite ends, each duct being connected with a supply duct Illa formed in and extending through theadjacent `arm Ha; in this arrangement the duct lll and the adjacent duct Ma supply fluid-such as oil-(which supply is under pressure) to the driving means or motor, indicated as an entirety at I5, to drive the wheel 9 in one direction and the duct I 4 and the adjacent duct Ida supply fluid to the driving means or motor I5 to drive the wheel in the opposite direction. The hydraulic rotary motor consists of a stator I 6 fixed to the axle Il and having an outer wall eccentric to the axis of the axle I I, as shown at |50: and a rotor l1 suitably fixed to the rim 9a for the wheel 9', the rim Sa being preferably provided with a tire of the solid rubber type. The rotor Il and wheel 9 are mounted to rotate on the axle II in the following manner; I8 indicates cup shaped hub members rigidly secured to the opposite ends of the rotor I1 by cap screws Isa. The hub members IB are interiorly shaped to accommodate suitable anti-friction bearings I9, the inner end of the inner race of each bearing being seated against an annular shoulder provided on the axle I I, and its outer end being biased inwardly by ,a coiled spring lSa interposed between it and the outer end wall of the adjacent hub member I8. Annular disks 2B, which are interposed between the rotor I'I and hub members I8 and fixed thereto by the screws la, extend inwardly beyond the rotor I'I to engage the inner ends of the outer races for the bearings I9, and maintain them in theirV seats provided on the inner walls of the hub members I8. The stator I6 is mounted between the disks 28, which prevent endwise movement thereof longitudinally of the axle.

. The inner wall of the rotor l'I is formed with a plurality of cylindrical sockets I'Ia disposed parallel to and equal distances from the axis of the axle H and each oscillatably supporting therein a pin lla.' to which is rigidly secured a follower I lb. Each follower extends into the chamber be tween the rotor l1 and stator I6 and rides the surface of the latter as the rotor I 1 rotates. The inner wall of the rotor I1 is recessed opposite the outer end of each follower, .as shown at I'Ib, to accommodate the swinging movement of the follower as it rides the eccentric portion of the stator It` Each follower I'Ib is biased inwardly about the axis of the adjacent pin Ila by a plunger llc slidably mounted in an opening Ilc formed in the rotor I'I. Each plunger I'Ic is preferably hollow to form a seat for the inner end of a spring II'd, its outer end abutting a plug IId' threaded into the outer end portion of the adjacent opening I'Ic. As will be observed from Figs. 4 and 5, I provide two sets of followers IIb, the followers of each set being uniformly spaced about the axle i I and each follower of one set being disposed between two followers of the other set; also, that the followers IIb of one set extend in a clockwise direction and those of the other set extend in a counter-clockwise direction (as viewed in Figs. e and5). Accordingly, fluid supplied through ducts If a, l. and a port Ma: formed in and leading through the axle II and stator I6 and having its outlet at one side of the eccentric I Er will apply high pressure to the followers I'Ib which extend counter-clockwise to rotate the rotor I7 (clockwise as viewed in Figs. 4 and 5) the supplied fluid being discharged on the low pressure side through a port Illa," at the opposite side of the eccentric and formed in and leading through the stator I6 and axle II and connected to the duct Ill (see Fig. 5); likewise, fluid supplied through ducts Illa, I4 and port I' will apply high pressure to the followers I'Ib which extend clockwise to rotate the rotor I'I (counter clockwise as viewed in Figs. 4 and 5), the supplied fluid being discharged on the low pressure side through the port Ma: and ducts I4, Illa. From the foregoing description it will be noted that by controlling the flow of the fluid, the motor i5 may be driven in either direction. It will be understood that upon the admission of the fluid through one port to the rotor I'I, pressure is initially applied to one active follower I'Ib and then progressively to the correspondingly positioned followers as the rotor rotates and that this pressure continues until the supplied fluid is discharged through the other port, whereas the oppositely disposed followers' I'Ib willyield in the direction of fluid flow in opposition to the springs I'Id to permit the fluid pressure to be maintained on the active followers until it is discharged through the latter port. By preference I provide at opposite sides of the eccentric ltr two ports Mr, Ism', respectively, so that the pressure may be applied to two active followers substantially simultaneously.

The fluid supply for the motor I5 consists of a tank 2| for holding a supply of fluid, fixed to the disk I2, a rotary pump indicated as an entirety at 22, driven by the motor 6, for circulating the fluid, a valve mechanism indicated as an entirety at 23 for controlling the iluid supply to the ducts Ita and operating means (later referred to) for the valve mechanism 23. The top wall of the tank 2l has secured to it a plate 23', (see Fig. l) which is provided with an up-standing shaft in co-axial relation with the axis of the ring bearing I3 and rotatably mounted in a suitable bearing carried by a collar which is suitably fixed to a base plate 24h rigidly secured to a bracket 24e carried by the upper end portion of the wall 1. The upper end portion of the shaft is screw threaded to take a nut 23d, whichvwhen -tightened co-operates with the ing'bearing I3 to rotatably support thewheel 9" ancl'motorI l5 and par-tsKA carried by `the'disk 'l2 inthe frame-section lb'and maintain Ythem against=vertical movement rela tivetothelatter. The casingf-for the pump 22 is bolted' directly totheside'wallf of the tank and preferably consistsv of an upper sectionEZa, a

tion Abv dowel pins 22g and secured toeether'by bolts. The members 22d'support bear-ings (pret.- erably of the anti-friction type) for `the-shaftsV 22e for suitable impe1lers22f,'one of said shafts bingextended' upwardly andI directly coupled tofthe shaftk of theimotor E; The upper-casingr` section 22a is formed with arecess 22o int regisY tryf'with Aan openingin thefsid wall of the tanto 2l and connected to a ductZZr'leadir-ig into onef sideof the 'pump chamber, whereas thesidesecition 22e is formed with anv outlet 22e', remote:

from the' outlet Aend of the duct 22x; connected toa pipe 222, which leads to the'valve'mechanism 23, as shownV in Figs. l and 2. Theu'pper pump section preferably terminates 'in an inverted bell-- shaped wall 22m' which is secured to the lower end of the'motor. y

The valvernechar'iism` 23 isfprovided with two separately operating valves, whereby they fluid' may be supplied: to the motorA l5 to' drive theI Wheel S" in either direction, and isconstructed:

to operatey as follows: When thevalve' elementsA are in neutral Aor normal position, the fluid is by`passed`through the valve casingand" is ree turned to the tank 2|, this retinnfpreferably bein'g'throu'gh a valvel mechanism 25ffor con# trolling the materialA handling` mechanism 3r tooperate the latter whenthetruck" is at rest,` whereby'separate fluid connections between the pump 22, the valve' mechanism 25; and tank 2l are eliminated, since no occasion would arisei for driving the traction wheelV Si and -simultane`-r ously operating the mechanism 3` to raise it. TheA casingl for thevalvemechanism 23 is mounted on the front wall ofthe tanlr 2i and preferably formed in sections and provided" therein-fwth iow channels'as follows: 2B indica-tes a'trans` vers'e' channel having-at its* upper lend an ex tended channel 2'a parallel to the upper portion ofthe channel 26. 2'! indicates a supplemental transverse channel. 2B indicates,l an ioutlet cham` nel leadingy to van outlet 28a, which is connected to a pipe 22. The pipe'ZS isconne'ctedto the valve' mechanism 25; from which theE fluid is returned to the tank 2l or utilizedftooperate thel load handling mechanism 3, as hereinafter set forth. 35i indicates the'inlet to which vthe supply pipe 22a for the fluid'is connected, for supplying fluid to the channels 26, 2Ea. 3l, 32, indicatey flow channelsconnected through outlets to pipes 3l', 32', respectively, the pipe'- 3l being con nected to the duct lllawhich is connected with the duct le", to drive thev wheel s in the"direction to effect forward travel-.of thev truck when the'valve element (indicatedas an entiretyfatt) is opere ated and the pipe 3:2" heingconnecte'cl to thev duct Ida which is connected to the duct Mto drive the Wheel 9 in the opposite or rearward direction when the Valveelement (indicated as 'an entirety at33) is operated. As will be observed, when fluid is supplied through the pipe 3 l to the motor l5' for forwardtrucktraveh the ud vin theductsi4", Ma, vis forced 'bythe' motor back through pipe 32 for return fiowto theY tank-2iand whenfthe fluid is supplied through pipe 32' toflthemotor l5.c for re'arward' truck-Ptravel, thel fluidi. in the ducts-1 I4, Ma; is forcedby-the motor back through pillet 3 lvfor returnvr flow to the tank 2 l', the valve4 mechanism 23;.beingconstructed-as will later bel set forth`,'to provide for-thisY return fluid ow to thusV eliminate 'separate flowvconnections from the motorl IS'to the-tank 2l. The channel 3l is provided wit-hbranch channels 3io; 2lb, 31e, whereas the channel 32 is provided' with branch channels "32a, 32h; 32e. 34 indicates a return owchannel'for the fluidv having an outlet 31ktI Whichregisterswith an" open-ing formed in the` adjacent wall' of the tank` 2 I. 35findicates alongitudinally: extendingv opening in linev with andv connectedwith Ithe channels 212Go, 26, Sie, 3Ib,' .-and '3rd, the'wall ofA the opening 35, between 'certain' of said'branch "channels, forming'a guidefor the *valve element-33 andYA flow ports for thefiu-id between said channels dependent :upon they position of the-*valveelement-SS. Sindicates a longitudinally eXtend-ingopening in line with and" connected "with the channels 28, 2l,- 26, 32e, 32h; 341',Y 32d, the'wall of.l the opening '33, between cer tain of said'branchchannels, formingr a-guidefor Athe valve element 33 and flow por-ts "between said channels dependent upon the position of -thef valve elementtt. The outer endof the valveY elementr 3,3 when in neutral 'position' (seevlia.I 6^) terminates in the channel SIb, so as'to permitvv fluid iiow from the pipe 3 I l through thechannels- 3m, 3|, Sib, and opening; (l5-to the'channel 34,

but when the valve element- 33=is operatedias laterfsetforth' toward 'the -leftas viewed in vFig-` f.' 6), thefopening ,35 between the chan-nels Sib, 34;- is'closed.- Asy shown, portions of the valve ele-'- ment 33 are reducedto form annular recesses. 33d" the opposite outer'end walls of which provide cutfoffs 321),- 33h. Also, as shown,` portions ofthe Vvalve elementk 33 arered-uced to'forin' annular recesses 33o, 33e', the opposite outer endw'ails of which, provide'jcutwis 33d, 33d', and-the outersend of Atlfievalve element, when 'in neutral position, terminates in the lchannel'32h so'as to permit fluid flow from thev pipe 32' through the channels 32a, .32, YZ322;l and.' opening 3S nel e but when the valve' element v23 is operated (as latersetf'orthtoward'the left'as viewed. inl Figs) the opening 'between'lthe channels 32h.r 3ft,y is closed.

When both valved elements V33, 33', are in vneutral position'as shownin Fig; 6) and motor 5 is operating to drive the pump22'theuid from the supply 'pipe'22e flows through channel 26a, recess 33a', channel 21, recess 33o', channel 28 and pipe 2&5 ahdreturns'to thetanl;y 2l, as' already set forth. If valve element 33 vis operated, cut-off 33h closes'the channel cut-off 33h opens the connection :between the channels 2f, 3io, and' the outer'end--of the'valvefelement closes the "con-4 nections between the channel 3i b and channel 3d', so' that the huidv from supply pipe' 22a flows through channel 25, recess 33a, channel 3io, channel :3l -andfchannelislm .to the pipe Sli to one side of the'motor= l5' and from the other side of` to the chan-- 32, channel 32a and pipe 32' to the opposite side of the motor I and from the first mentioned side thereof through pipe 3I, channel 3m, channel 3l, channel SIb, opening 35, channel 35 and opening 34a to the tank 2|. If both valve elements 33, 33', are simultaneously operated the iiuid will be supplied to both sides of the motor I5 through the respective channels as above set forth, the effect of which is to stop it and hence stop the Wheel 9'; accordingly, when the truck is in motion, due to operation of one of the valve elements, the other valve element may be operated and thus provide fluid pressure from the supply pipe 222 in opposition to the return flow of fluid from the motor I5, the effect of which is to retard the operation of the motor and to slow down the rotation of the wheel 9 and bring the motor to a stop, if desired. It will thus be observed that When the truck is being driven in either direction, the valve elements 33, 33', may be operated to increase or decrease the speed of the truck as well as provide a braking effect whether the truck is traversing a level or inclined surface. In this arrangement mechanical braking elements for the Wheel or motor and a separate control therefor are eliminated. Due to the fact that the fluid system and motor rotor I1 are completely filled with fluid at all times, operation of either valve element 33, 33', insures quick starting, and operation of both elements insures ready braking and stoppage of the motor I5.

31, 31', indicates as entireties relief valve means mounted in the outer ends of the openings 35, 35, respectively, to relieve excessive pressure which may exist in the iiuid system at any time. As these valve means are similar in construction, one (valve means 31) only will be referred to. The valve means 31 consists of a sealing member 31a seated in the opening 35 and formed with a through opening, the inner end of which serves as a seat for a, valve element 31h. The valve element 31h is provided with a hollow shank 37o which slidably fits the opening through the element 31a. The outer end of the shank 31o is open to admit fluid thereinto from the channel Sla and its side Wall is formed with a port (preferably two ports, in disalinement longitudinally) to connect the opening in the shank with the channel 34 when the valve element 31h is unseated. The valve element 31h is normally held in engagement with its seat by an expansion spring 38 interposed between it and the valve element 33, the outer end portion of which is formed with an inwardly extending recess 33a: to accommodate the spring and permit a long spring to be employed. In this arrangement, each spring 38 is put under compression when the adjacent valve element 33 or 33' is operated to prevent operation of the relief valve when the fluid is being supplied to the motor I5 through the pipe 3I' or pipe 32'.

The load handling mechanism 3 may consist of a single load carrying member for loads, but by preference such support consists of spaced, flxedly related parallel load carrying members adapted to be raised and lowered hydraulically by a reciprocatable piston mounted in a cylinder 46 and operatively connected to levers 4I, which in turn are connected to the yokes 48d to swing the wheels I5 about the shafts 49 for the yokes.

Due to the fact that the truck is guided or steered by the operative through the instrumentality of a manually operated element, indicated as an entirety at 52, the controls (later referred to) for the motor I5 and material handling 6 and uid circulatingpump 22 are mounted on the rotatable disk I2, and the fluid connection 41 between the valve 25 and the cylinder 45 is preferably provided in the joint or bearing elements (already referred to),'whereby iiuid ow between the valve 25 and cylinder 46 is provided for while permitting steering of the wheel 9'.

The arms II a depend from a bracket lixed to the disk I2 and are provided with integral skirts I ib, which in turn are related to side skirts I lb', that terminate in a pair of spaced, parallelly related outwardly extending supports IIc. The guide or steering element 52 consists of a tubular member 93, a loop shaped member 93a at its lower end and a housing member 93h at its upper end. The side walls of the loop shaped member 93a are fulcrumed on and between the supports Ilc (see Fig. 2), whereby the steering element 52 may be bodily swung forwardly into convenient position to be grasped by the operative for guiding and controlling the movement of the truck. The lower end of the member 93a is pivotally connected to the outer end of a rod 94; the inner end portion of the rod is slidable in a fitting 34a suitably mounted on a rock shaft which is supported in the skirts Hb'. A spring 94h coiled around the rod 34 and interposed between the fitting 93a and the knuckle at the outer end of the rod 94 normallly tends to swing the element 52 upwardly and maintain it in vertical position as shown in Fig. l. The construction of the steering element 52 provides for the mounting of the controlling devices 95, 95a, for the valve mechanism 23 and a controlling device 96 for the valve mechanism 25 at or adjacent its outer end, whereby the operation of the rotary motor I5 and material handling mechanism 3 may be effected by the operative independently of the position of the steering element, so that bodily movement thereof is not required to operate or stop the motor I5 and the mechanism 3. The controlling devices 95, 95a, consist of handles rotatably mounted in the side walls of the housing member 93h (preferably in axial relation) and extending laterally therefrom. The inner end of each handle is provided with an arm 93e, the outer end of which is pivotally connected to the upper end of a rod 91. The lower end of the rod 91, which is connected to the handle 95a, is pivotally connected to the outer end of a bell-crank 91a, which is mounted on the adjacent skirt IIb', and the bell-crank 91a is pivotally connected to the outer end of a link 31h which in turn is connected to the valve element 33. Accordingly, by rotation of the handle 95a counter-clockwise, the valve element 33 is operated toward the left (as viewed in Fig. 6) to supply fluid to the motor I5, as already set forth. The lower end of the rod 91, which is connected to the handle 35, is pivotally connected to the outer end of a bell-crank 91a', mounted on the adjacent skirt IIb', the inner end of the bellcrank being pivotally connected to a link Sib', which in turn is connected to the valve element 33'; accordingly, by rotation of the handle S5 counter-clockwise the valve element 33' is operated toward the left (as viewed in Fig. 6) to supply uid to the motor I5, as already set forth.

As shown in Fig. 6, each link 91h, 91h', is pivotally connected to a thrust element 91:13' threaded in the outer end portion of the adjacent valve element and locked by a nut 91m", whereby the operating connections between each handle 95, 95a, and the adjacent valve element may be adjusted to insure accurate operation of the latter.

The'controlling element- 96"consistsfofra" handle pivotally mountedronazbracket SB'acarried vby the steering elementv 52A and provided with'an arm 96h pivotally connected to therupper endof a rod 91e. The lowerv end of the`rod9'ic is pivotally connectedto the outerend'of .a'bell-crank 9B (the axis of the pivot'for the lower end ofthe rod 91o beingin line with the axis on which the element 52 swings) fulcrumed on a stud shaft carried by theadjacent shirt i Ib.` The inner end 98a of the bell-crank 98 is pivctally connected to the outer end of a link 91e which is pivotally connected to the valve element or plunger 25d for the valve mechanism 25v for controlling the latter.

9S indicates a casingv orr housing extending around the parts mountedA on,` the disk- IZf and xed tothe' side bars forming' the frame/section lbfandfBQa, 99a', indicate hoods' fitting overthe casing 99 and battery 5, thehoods being-hinged together..

From the foregoing description it willbe'observed that the pressure fluid system provides for the circulation of the fluid by continuous operation of the electric motor to drive the pump 22 and return thereof to the tank 2l during the periods when the truck is not being driven or the load handling mechanism 3 is in either lowered or elevated position. This operation may be carried out by providing a suitable switch to close the motor circuit through a contacter iti?. I prefer however to maintain the electric motor 5 at rest during these periods and to automatically close the circuit to the motor 6 and drive it each time either valve mechanism 23 or 25 is operated. In this preferred arrangement I provide a switch iil adjacent to each valve plunger 33, 33 (see Fig. l-these switches for valve plungers 33, 33', shown diagrammatically in Fig. 9), so that when either thereof is operated to supply uid pressure to the motor l5, the adjacent circuit l2 will operate the contacter IGI! to close the motor circuit ifi?, for the motor 6. Each switch consists of suitable contacts in a housing and a resilient switch arm Il normally disengaged from the contacts, the outer end portion of the arm being disposed in the path of movement of a collar |64 fixed to the adjacent valve plunger 33 by the nut 91x, so that operation of the plunger will swing the arm HH inwardly and close the circuit lZ. The corresponding switch, indicated at HB5 (see Fig. 9), for the valve plunger 25d of valve mechanism 25, is provided with a resilient contact closing arm lii, arranged to be operated by a cam fixed to the valve plunger L25d when the latter is moved downwardly, such operation serving to close the circuit IES and operate the contactor li. In the arrangements above described, economical use of the current supplied by the battery 5 results, since the electric motor 5 is driven only when huid pressure is required and since the fluid system remains at all times filled with fluid, no delay occurs in operating the motor I5 or load handling mechanism 3 upon operation of the valve mechanisms which control the fluid supply therefor. This application is a division of my application Ser. No. 604,565, filed July 12, 1945.

To those skilled in the art to which my invention relates many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. My disclosures and the description herein are purely illustrative land are not intended to be in any sense limiting.

1".'.In atruck having avframe,.aicombinedtraction-1and.'steerablefmechanisrn; rotatably. mounted inone end-:portion ofi said: frame, said traction and 1 steerable'f' mechanism. including:l an axle, a traction wheelr rotatably'mounted.onasaid axle intermediate. its. opposite ends. andiahydraulic reversible rotary motori between said: axle and wheel', said axle ,beingy formed" with liquid circulating ducts,Ileadinginwardly from-itsfopposite endipor-tions, and means for ysupplying liquid to and from said: ducts..v for` driving; saidmotor in either direction; a'valve mechanism forcontrolling the flow; of the liquid' in either direction, and an element connected to said rst mentioned mecl anism'for'steeringthe truck during oper-ation thereof.

2. A truckv as. claimedin-clai-m l wherein the valve mechanism is provided with separate'control valve elements operable to control the supply ofliquid to either side of said` motor or both sides .thereof simultaneously.

3L In a truck, the combination with a frame, of a combined traction and steerable mechanism rotatably mounted in one end portion of said frame, said traction and steerable mechanism including an axle, a traction wheel rotatably mounted on said axle intermediate its opposite ends and a hydraulic reversible rotary motor between said axle and wheel, said axle being formed with liquid circulating ducts leading inwardly from its opposite end portions, and means for supplying liquid under pressure to and from said motor for driving it in either direction, a valve mechanism for controlling the flow of the liquid in either direction, and an element connected to said first mentioned mechanism for steering the truck during operation thereof.

4. A truck comprising a frame, Wheels for supporting said frame, a hydraulically operated motor for driving one of said wheels, said motor consisting of a stator xed to the axle for said driven wheel and having an eccentric outer surface, a rotor fixed to said wheel, sets of followers swingably mounted at their outer ends on said rotor on an imaginary circle concentric to said axle and extending into the space between said stator and rotor for engagement with the outer surface of said stator, and means for yieldingly maintaining the inner ends of said followers in engagement with said stator, each follower of each set being positioned between two followers of the other set and all of the followers of one set extending in a clockwise direction and all of the followers of the other set extending in a counter-clockwise direction, a .source of liquid supply under pressure, separate liquid supply ducts leading through the axle for said driven Wheel and having a connection t0 the space between said rotor and said stator at opposite sides, respectively, of the throw of said stator, a valve mechanism for selectively controlling the iiow of liquid to each of said connections, and means for operating said valve mechanism to supply liquid to each of said connections.

5. A truck as claimed in claim 4 wherein said valve mechanism is provided with separate valve elements operable independently or simultaneously, whereby liquid may be supplied to either of said connections or to both connections simultaneously.

6. A traction wheel for a truck comprising an axle connected at its opposite ends to the truck frame, a tired rim surrounding said axle, a hydraulically operated motor between said axle and rim and consisting of a stator xed to said axle and having an eccentric outer surface, a rotor Within and xed to said rim, hub members at opposite sides of said motor fixed to said rotor, anti-friction bearings between said hub members and said axle, followers carried by said rotor and extending into the space between said rotor and said stator and arranged to engage the latter, said axle being formed with a duct connected at its inner end to a port leading through said stator into the space between it and said rotor, and valve controlled means for supplying liquid under pressure to the outer end of said duct.

7. In a truck having a frame and wheels for supporting one end of said frame, a combined traction and steerable mechanism for supporting the opposite end of said frame, said mechanism comprising a disk rotatably mounted in said frame, a traction wheel having an axle below and connected to said disk, a hydraulically operated rotary motor disposed between said axle and said wheel, means carried by said disk for supplying 12 liquid under pressure and liquid connections between said liquid supply means and each side of said motor, a portion of each connection leading through said wheel axle, a valve mechanism on said disk for controlling the iiow of the liquid to said motor, and a manually operated device for rotating said disk to steer the truck.

FRANK STONER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 883,188 Gause et al Mar. 31, 1908 1,380,596 Rudqvist June 7, 1921 1,803,932 Dooley May 5, 1931 2,320,600 Howell June 1, 1943 2,325,396 Hastings, Jr July 27, 1943 2,359,493 Schreck Oct. 3, 1944 2,417,018 Schroeder Mar. 4, 1947 

